The present invention pertains to the field of semiconductor lasers.
Semiconductor lasers typically provide laser output having a very narrow spectrum. These lasers are typically thought to be monochromatic, the laser radiation frequency corresponding to the energy between the valence and the conduction bands in the material. Attempts to produce laser radiation from electron levels at substantial distances away from the conduction bandgap have met with little success. In particular, many previous attempts to fill the conduction band have resulted in material damage.
Furthermore, there have been attempts to study hot electrons under high intensity photoexcitation of semiconductors. These studies have generally kept the semiconductor material at very low temperatures and have not produced laser action. See for example articles entitled: "Hot Electrons and Photons Under High Intensity Photoexcitation of Semiconductors", Solid State Electronics, Vol. 21, 1978, pp. 43-50 by J. Shah, "Pico-Second Spectroscopy of Highly Excited CdSe and CdS-I .beta. II High Density Excitation System", Solid State Comm., Vol. 24, 1977, pp. 833-840, by M. Hayashi, H. Saito, and S. Shionoya and "Luminescence Due to Metallic Electron-Hole Liquid InGaAs", Solid State Comm., Vol. 14, 1974, pp. 245-248, by T. Moriya and T. Kushida.
Even results showing stimulated emission from thin films of semiconductor material disclosed in articles entitled "Dependence of Stimulated Emission from Thin PbS.sub.1-x Se.sub.x Films On Temperature in the 50.degree.-300.degree. K. Range", Sov. Phys. Semicond., Vol. 13, No. 9, September 1979, pp. 988-991, by A. E. Yunovich, A. S. Averyushkin, I. A. Drozel, and V. G. Ogneva and "Lasing in ZnTe, ZnSe, and CdS Single Crystals Excited by Ruby Laser Picosecond Pulses", Sov. J. Quantum Electron., Vol. 9, No. 10, October 1979, pp. 1305-1307, by V. P. Gribkovsku, V. A. Zaporozhchenko, V. A. Ivanov, A. V. Kochinsku, V. V. Parashchuk, and G. P. Yablonsku do not exhibit wide spectrum laser output.